Liver- and Spleen-Specific Immune Responses in Experimental Leishmania martiniquensis Infection in BALB/c Mice.

Leishmania martiniquensis is a neglected cause of an emerging leishmaniasis in many countries, including France, Germany, Switzerland, the United States of America, Myanmar, and Thailand, with different clinical manifestations ranging from asymptomatic, cutaneous (CL), visceral (VL), and atypically disseminated CL and VL. The persistence of parasites and the recurrence of the disease after treatment are challenges in controlling the disease. To explore efficient prophylaxis and therapy, this study aimed to investigate infection outcome and organ-specific immune responses after inoculation with L. martiniquensis (MHOM/TH/2011/PG; 5 x 106 promastigotes) in BALB/c mice via intravenous and intraperitoneal routes. A quantitative PCR technique, targeting L. martiniquensis ITS1, was primarily established to estimate the parasite burden. We found that the infection in the liver resolved; however, persistent infection was observed in the spleen. Histopathology with Leishmania-specific immunostaining revealed efficient hepatic granuloma formation, while splenic disorganization with parasitized macrophages at different locations was demonstrated. The mRNA expression of Th1 cytokines (IFN-γ, TNF-α, IL-12p40) and iNOS in the liver and spleen was upregulated. In addition, high expression of IL-10 was observed in the spleen in the chronic phase, revealing a significant moderate correlation with the parasite persistence [r(12) = 0.72, P = 0.009]. Further clarification of the mechanisms of persistent infection and experimental infection in immunosuppressed murine models are warranted.

A novel cystatin derived from Trichinella spiralis suppresses macrophage-mediated inflammatory responses.

Trichinella spiralis can modulate host immune responses to retain a suitable environment for its long-term survival. Incidentally, the parasite elicits regulatory effects through immunomodulatory molecule release, which can suppress host inflammation and may be used for the treatment of unrelated inflammatory diseases in someday. Here we identified and characterized a novel T. spiralis cystatin (TsCstN), which inhibits inflammation mediated by LPS-treated macrophages.Proteins contained in the excretory-secretory (ES) product of muscle-stage T. spiralis (ES-L1) were fractionated, and each was treated with mouse bone marrow-derived macrophages (mBMDMs) before LPS stimulation. The fractions that exhibited high immunomodulatory property by decreasing pro-inflammatory cytokines or increasing anti-inflammatory cytokines were identified by mass spectrometry. Incidentally, the conserved hypothetical protein (Tsp_04814) was selected for further characterization as it presented the most significant MS score. An annotation of Tsp_04814 using protein structural homology comparison suggested that it has high structural similarity to human cystatin E/M (TM score 0.690). The recombinant T. spiralis novel cystatin (rTsCstN) was expressed in Escherichia coli at a molecular weight of approximately 13 kDa. Mouse anti-rTsCstN polyclonal antibody (pAb) could detect native TsCstN in crude worm antigens (CWA) and ES-L1 and be predominantly localized in the stichosome and subcuticular cells. rTsCstN inhibited cysteine proteases in vitro, especially cathepsin L, at an optimal pH of 6. Besides, rTsCstN could be internalized into mBMDMs, which were mostly distributed in the cytoplasm and lysosome both before and after LPS stimulation. To evaluate the rTsCstN immunomodulatory properties on mBMDMs, rTsCstN was incubated with mBMDM before LPS stimulation; this demonstrated that rTsCstN suppressed pro-inflammatory cytokine production and MHC class II expression.T. spiralis L1-derived TsCstN was characterized as a novel cysteine protease inhibitor. The protein elicits an anti-inflammatory property by suppressing pro-inflammatory cytokines and interfering with the antigen presentation process through depletion of MHC class II expression.

Ungulate malaria parasites.

Haemosporida parasites of even-toed ungulates are diverse and globally distributed, but since their discovery in 1913 their characterization has relied exclusively on microscopy-based descriptions. In order to bring molecular approaches to bear on the identity and evolutionary relationships of ungulate malaria parasites, we conducted Plasmodium cytb-specific nested PCR surveys using blood from water buffalo in Vietnam and Thailand, and goats in Zambia. We found that Plasmodium is readily detectable from water buffalo in these countries, indicating that buffalo Plasmodium is distributed in a wider region than India, which is the only area in which buffalo Plasmodium has been reported. Two types (I and II) of Plasmodium sequences were identified from water buffalo and a third type (III) was isolated from goat. Morphology of the parasite was confirmed in Giemsa-reagent stained blood smears for the Type I sample. Complete mitochondrial DNA sequences were isolated and used to infer a phylogeny in which ungulate malaria parasites form a monophyletic clade within the Haemosporida, and branch prior to the clade containing bird, lizard and other mammalian Plasmodium. Thus it is likely that host switching of Plasmodium from birds to mammals occurred multiple times, with a switch to ungulates independently from other mammalian Plasmodium.